Ventilatory chemosensitive adaptations to intermittent hypoxic exposure with endurance training and detraining

The present study was performed to clarify the effects of intermittent expo sure to an altitude of 4,500 m with endurance training and detraining on ve ntilatory chemosensitivity. Seven subjects (sea-level group) trained at sea level at 70% maximal oxygen uptake ((V) over doto(2max)) for 30 min/day, 5 days/wk for 2 wk, whereas the other seven subjects (altitude group) traine d at the same relative intensity (70% altitude (V) over doto(2max)) in a hy pobaric chamber. (V) over doto(2max) hypoxic ventilatory response (HVR), an d hypercapnic ventilatory response, as an index of central hypercapnic chem osensitivity (HCVR) and as an index of peripheral chemosensitivity (HCVRSB) , were measured. In both groups (V) over doto(2max) increased significantly after training, and a significant loss of (V) over doto(2max) occurred dur ing 2 wk of detraining. HVR tended to increase in the altitude group but no t significantly, whereas it decreased significantly in the sea-level group after training. HCVR and HCVRSB did not change in each group. After detrain ing, HVR returned to the pretraining level in both groups. These results su ggest that ventilatory chemosensitivity to hypoxia is more variable by endu rance training and detraining than that to hypercapnia.